SEATTLE — Dairon Asprilla scored the deciding penalty as the Portland Timbers survived a wild second half and extra time to defeat the Seattle Sounders 4-2 in a shootout Thursday night and advance to the MLS Western Conference finals.

Seattle won the wild second leg of the conference semifinal matchup between the Cascadia rivals 3-2, scoring late in regulation to force extra time before both teams scored early in the extra session. Eventually, the sides decided the winner via penalties, although Portland initially believed it had won at the end of extra time because of scoring a second road goal in the match.

The celebration was premature as road goals are not a tiebreaker in extra time. But it became real minutes later when Asprilla beat Seattle goalkeeper Stefan Frei and sent Portland to the West finals for the first time since winning the MLS Cup in 2015.

Portland will face Sporting Kansas City or Real Salt Lake in the West finals.